System for generating coherent single-frequency single transverse mode light pulses

Abstract

A system is provided to generate coherent single-frequency and single transverse mode light pulses. A laser produces a linearly-polarized continuous wave beam defined by a single longitudinal and transverse mode. A first rotator processes the beam such that optical polarization is rotated during a first time period and not rotated during a second and third time period. A second rotator is operated during the first period to rotate optical polarization of the beam, during the second period to not rotate the beam, and during the third period to rotate the beam. An optical loop amplifies the beam during the first and second periods. An amplifier device can be added to the loop for amplification. A first beam splitter allows the beam to enter the loop and a second splitter directs the beam along the loop during the first and second periods and out of the loop during the third period.

What is claimed is: 
     
       1. A system for generating coherent single-frequency and single transverse mode light pulses, said system comprising:
 a laser capable of producing a linearly-polarized continuous wave laser beam as defined by a single longitudinal mode and a single transverse mode; 
 a first polarization rotator positioned to receive and process the laser beam with said first polarization rotator operable during a first time period to rotate optical polarization of the laser beam, and with said first polarization rotator operable during a second and third time period to not rotate optical polarization of the laser beam; 
 a second polarization rotator positioned to receive and process the laser beam from said first polarization rotator with said second polarization rotator operable during the first time period to rotate optical polarization of the laser beam, and with said second polarization rotator operable during the second period to not rotate optical polarization of the laser beam, and further with said second polarization rotator operable during the third period to rotate optical polarization of the laser beam; and 
 an optical amplification loop positioned to receive the laser beam emitted from said first polarization rotator and said second polarization rotator, said optical amplification loop capable of amplifying the laser beam received during the first and second time periods; 
 wherein said optical amplification loop includes an optical fiber loop amplifier positioned within said amplification loop; 
 wherein each of said first and second polarization rotators includes an electrically-controllable element selected from the group consisting of a Pockels cell and a Kerr cell. 
 
     
     
       2. A system as in  claim 1 , wherein said system further comprises:
 a first beam splitter positioned in said amplification loop between said first and second rotators wherein said first beam splitter is capable of allowing the laser beam to enter said amplification loop; and 
 a second beam splitter positioned in said amplification loop between said second rotator and said amplifier wherein said second beam splitter is capable of directing the laser beam processed by said first and second polarization rotators along said optical amplification loop during the first and second time periods and configured to eject the laser beam processed by said first and second polarization rotators out of said optical amplification loop during the third time period in order to obtain an output pulse.